1. Field of the Invention
The invention generally relates to the field of chromatographic analysis of samples and, more specifically, to the automatic handling of the sample during such analysis.
2. Background of the Invention
In general, the chromatographic analysis of samples containing components of varying molecular weight is not new. Such analysis separates the components of a sample into fractions of increasing or decreasing molecular weight by moving the sample, usually together with a solvent, through a device that is adapted to cause components of differing molecular weight to move at differing speeds. In a typical such device the capillary pathway is adapted so that components of a larger molecular weight move more slowly along the pathway than those of a lower molecular weight so that components of a lower molecular weight are delivered at the exit end of the capillary pathway first and components of a higher molecular weight are delivered later. The liquid may be moved through a capillary pathway by pressure or electrostatic forces, or both, and the adaptations that selectively control the movement of different size components along the pathway may involve the application of, for example, electric fields to a conductive capillary or the use of specialized polymers in the pathway. Fractions of the sample may then be assayed by known methods including, for example, laser induced fluorescence (LIF) and a variety of mass spectrographic processes.
Such devices normally provide useful results. However, the handling of the sample during such a process has been labor intensive and expensive. The sample is often collected on a resin that is held in a cartridge or capillary tray capable of withstanding high pressures. The cartridge is placed in a capillary pathway by means of high-pressure couplings, usually by hand. There is a need for a system capable of automatically moving samples into and out of a separation pathway.
The samples to be analyzed are often very small in volume and are mismatched with relatively large resin-containing cartridges that are commercially available. Resin-containing removable pipette tips for use with small volumes of materials are commercially available but have not been useful as components of high-pressure chromatography systems. There is a need for a system including relatively small sample-supply components.
Another problem of the prior art, especially in the analysis of low amounts of tryptic digests commonly used in proteomics analysis, is sample loss associated with nonspecific adsorption. Additionally, the use of nanoscale chromatography has practical limits on the volume of sample that can be loaded onto a resin column. It is an object of this invention to provide a sample-supply component that is useful in high-pressure liquid chromatography devices, that is suitable for use with small samples and that can be moved into and out of a capillary pathway easily and automatically.
It is another object of this invention to provide a sample-handling system suitable for automatic or robotic movement of small samples into and out of a capillary pathway.